Help wanted: Why do maths/radix2_fft.py test results change on Python 3.14 beta? #12729

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1. cclauss

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   on May 12, 2025
2. cclauss

   changed the title [-]Help requested: Why do maths/radix2_fft.py test results change on Python 3.14 beta?[/-] [+]Help wanted: Why do maths/radix2_fft.py test results change on Python 3.14 beta?[/+] on May 12, 2025
3. cclauss

   pinned this issue on May 12, 2025
4. MaximSmolskiy commented on May 13, 2025

   

   MaximSmolskiy

   on May 13, 2025

   Last edited by cclauss

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   @cclauss In Python 3.14 Release Notes (https://docs.python.org/3.14/whatsnew/3.14.html) there are mentions of changes related to complex numbers:

   • Implement mixed-mode arithmetic rules combining real and complex numbers as specified by C standards since C99. (Contributed by Sergey B Kirpichev in gh-69639.)

   This may be the reason for changes in the doctests.
5. cclauss commented on May 14, 2025

   

   cclauss

   on May 14, 2025

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   @skirpichev
6. skirpichev commented on May 14, 2025

   

   skirpichev

   on May 14, 2025

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   JFR, above pr was merged not before latest beta. Did you test alphas?
7. cclauss commented on May 14, 2025

   

   cclauss

   on May 14, 2025

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   https://github.com/TheAlgorithms/Python/actions/runs/14991034991/job/42114180325#step:5:20 This is beta 1.

   Or is uv using a different Py3.14?
8. skirpichev commented on May 14, 2025

   

   skirpichev

   on May 14, 2025

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   My question was did you test 3.14 alphas?
9. skirpichev commented on May 14, 2025

   

   skirpichev

   on May 14, 2025

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   Anyway, so far I can guess this might be related to:

           inverce_c = [round(x[0].real, 8) + round(x[0].imag, 8) * 1j for x in inverce_c]

   Probably, you want rather complex(round(x[0].real, 8), round(x[0].imag, 8)). But with above pattern you can get different answers on 3.14 and 3.13. Example:

   Python 3.14.0a7 (tags/v3.14.0a7:29af6cee02, Apr  9 2025, 12:48:04) [GCC 12.2.0] on linux
   Type "help", "copyright", "credits" or "license" for more information.
   >>> 1 + (-0.0)*1j
   (1-0j)
   Python 3.13.3 (tags/v3.13.3:6280bb5478, Apr  9 2025, 10:07:49) [GCC 12.2.0] on linux
   Type "help", "copyright", "credits" or "license" for more information.
   >>> 1 + (-0.0)*1j
   (1+0j)

   Obviously, the last answer is incorrect as a replacement of complex(1, -0.0).
10. cclauss

    added a commit that references this issue on May 28, 2025

    maths/radix2_fft.py: Fix calculation for Python 3.14

    ...

    7e7af22
11. cclauss

    closed this as completedin #12772on May 29, 2025
12. cclauss

    added a commit that references this issue on May 29, 2025

    maths/radix2_fft.py: Fix calculation for Python 3.14 (#12772)

    ...

    d0d7f0b
13. cclauss

    unpinned this issue on Jul 30, 2025
14. favdevtech

    added a commit that references this issue on Feb 16, 2026

    maths/radix2_fft.py: Fix calculation for Python 3.14 (#12772)

    ...

    a101333